KR20180018782A - Head-up display system - Google Patents

Abstract

There is provided an electro-optic assembly configured to be operatively connected to a head-up display system of a vehicle, comprising a first substrate having a first surface and a second surface, and a second substrate having a third surface and a fourth surface. The first substrate and the second substrate are configured to be held in a parallel spaced relationship and to be sealed around the periphery of the first and second substrates. An anti-reflective coating is positioned on the third surface of the second partially reflective, partially transparent substrate. The semipermeable coating is located on at least one of the first and second surfaces and the electrochromic medium is positioned between the second surface of the first substrate and the third surface of the second substrate. The electro-optic assembly is configured to reflect an image from the projector of the head-up display system of the vehicle.

Description

Head-up display system

This disclosure generally relates to an electro-optical assembly, more particularly a head-up display having an electro-optic assembly.

According to an aspect of the present disclosure there is provided a method of operating a head-up display system, comprising a first substrate having a first surface and a second surface, and a second substrate having a third surface and a fourth surface, An electro-optic assembly is provided which is configured to be adapted. The first substrate and the second substrate are configured to be held in a parallel spaced relationship and to be sealed around the periphery of the first and second substrates. A transflective coating is positioned on at least one of the first and second surfaces of the first substrate. An anti-reflection electrode is positioned on at least one of the second and third surfaces. An anti-reflective coating is placed on the fourth surface. An electrochromic medium is positioned between the second surface of the first substrate and the third surface of the second substrate. The electro-optic assembly is configured to reflect an image from the projector of the head-up display system of the vehicle.

According to another aspect of the present disclosure there is provided a method of operating a head-up display system, comprising a first substrate having a first surface and a second surface, and a second substrate having a third surface and a fourth surface, An electro-optic assembly is provided which is configured to be adapted. The first substrate and the second substrate are configured to be positioned in a parallel spaced relationship and to be sealed along the periphery of the first and second substrates. A semipermeable coating is positioned on at least one of the first and second surfaces. The semipermeable coating has a low-absorption layer and at least a first metal layer. An electrochromic medium is positioned between the second surface of the first substrate and the third surface of the second substrate. The reflectance is not substantially changed. The electro-optic assembly is configured to control the transmittance from a transparent state to a dark state, and the electro-optic assembly is configured to reflect an image from the projector of the head-up display system of the vehicle.

According to yet another aspect of the present disclosure, there is provided an electro-optic assembly comprising a substrate defining a first surface and a second surface. A semipermeable layer is positioned on the first surface of the first substrate. The semipermeable layer has a metal-dielectric-metal (MDM) structure with a reflectivity of about 15% to 35%. The second substrate defines a third surface and a fourth surface. An anti-reflection electrode is positioned on the second surface of the first substrate and the third surface of the second substrate. The antireflective electrode has a transparent conducting oxide and an antireflective coating on the fourth surface of the second substrate. The electrochromic medium is positioned between the second surface of the first substrate and the third surface of the second substrate and can be operated between a transparent state and a dark state. The reflectance from the antireflective coating and antireflective electrode is less than 1% each. The transmittance in the transparent state is about 24% to 45%, and the transmittance in the dark state is less than about 7.5%. The electro-optic assembly is configured to operably connect to a head-up display system for a vehicle.

These and other features, advantages, and objects of the present disclosure will be better understood and appreciated by those skilled in the art with reference to the following detailed description, the claims, and the accompanying drawings.

In the drawing:
1 is a front perspective view of a head-up display system including an electro-optic-element, according to one example;
2 is a front perspective view of a head-up display system including an electro-optic-element, according to another example;
Figure 3 is a cross-sectional view of the electro-optical assembly of Figure 1 over line III;
Figures 4A and 4B illustrate eye-weighted transmittance versus reflectance for a single metal layer on a first surface of an electro-optic assembly;
Figure 5 shows the transmittance versus reflectivity relationship for a single layer of Cr on the first surface of the electro-optic assembly and for a double layer of ITO / Cr dual layer;
Figure 6 shows the transmittance versus reflectance relationship for the Cr / ITO / Cr multilayer transflective portion on the first electro-optic assembly surface;
Figure 7 shows the transmittance versus reflectance relationship for a single layer of a diamond-like-carbon (DLC) coating on an electro-optic assembly;
Figure 8 shows the transmittance versus reflectivity relationship for a single layer of ITO and an ITO / TiO2 double layer on the first surface of the electro-optic assembly;
Figure 9 shows the eye sensitivity weighted reflectance according to the thickness of the metal AR coating;
Figure 10 shows the spectral reflectance of a dielectric multilayer reflective coating;
Figure 11 shows the reflectance versus wavelength dependence of metal and dielectric AR coatings compared to raw glass.

This illustrated embodiment is primarily a combination of method steps and apparatus components for an electro-optical assembly, and more particularly for a head-up display system having an electro-optic assembly. Accordingly, device components and method steps may be presented as appropriate in the figures, which are indicative of only those specific details suited to an understanding of the implementations of the present disclosure, so that those skilled in the art having the benefit of the description herein will readily And does not obscure the disclosure with clarity details. Also, similar numbers in the description and drawings represent like elements.

The terms "top", "bottom", "right", "left", "rear", "forward", "vertical", "horizontal", and their derivatives, Will refer to the surface of the element closer to the intended observer of the electro-optical head-up display system, and the term "rear" Will refer to the surface of an element further away from the intended observer of the head-up display system. However, it should be understood that this disclosure, on the contrary, may assume various alternative orientations, unless explicitly specified otherwise. It is to be understood that the specific devices and processes illustrated in the accompanying drawings and described in the following description are merely exemplary implementations of the concepts of the present invention as defined in the appended claims. Certain dimensions and other physical characteristics with respect to the embodiments described should not be considered as limiting unless the claims are explicitly stated otherwise.

The word "comprise", "comprises", "comprising", or any other variation thereof, means that a process, method, article, or apparatus, including a list of elements, Quot; is intended to encompass a non-exclusive inclusion as well as including other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceding "comprises" does not exclude the presence of additional, identical elements in the process, method, article, or apparatus that comprises the element, without further constraints.

With reference to Figures 1-3, reference numeral ' 10 ' generally refers to an electro-optic assembly. The electro-optical assembly 10 may be utilized within the head-up display system 14 of the vehicle 18. [ The electro-optical assembly 10 may have a first partially reflective, partially transmissive glass substrate 22 and a second partially reflective, partially transmissive glass substrate 26. The first substrate 22 may have a first surface 22A and a second surface 22B. The second substrate 26 may have a third surface 26A and a fourth surface 26B. The first and second substrates 22 and 26 may be positioned in a parallel spaced relationship and may have a seal 30 substantially around the periphery of the first and second substrates 22 and 26. The first substrate 22 and the second substrate 26 define a cavity 34. The electro-optic medium 38 is present in the cavity 34 between the first substrate 22 and the second substrate 26. In at least one example, the electro-optic assembly 10 is configured to have unaltered reflectivity and varying transmittance. The "transparent state" of the electro-optical assembly 10 refers to the condition of maximum transmittance. Activation of the electro-optic medium 38 may reduce the transmittance of the electro-optic assembly 10 to a "dark state ". The "low end" transmittance refers to the minimum transmittance that can be achieved by the electro-optical assembly 10.

By way of example and not limitation, the electro-optical assembly 10 may be included within the head-up display (HUD) system 14 of the vehicle 18. [ In such an example, the electro-optic element 10 may function as a combiner screen for reflecting a primary image projected by the projector 46. The electro-optical assembly 10 can be controlled to change the light transmission amount based on the input from the control circuit. For example, in a daytime condition, the electro-optical assembly 10 may be darkened to improve or increase the contrast ratio and may improve the visibility of the information projected onto the electro-optical assembly 10 from the projector 46 . The contrast ratio may represent the ratio of the primary reflected image from the projector 46 and the light transmitted through the electro-optic assembly 10 (e.g., in a transparent or dark state).

The head-up display system 14 may be used in a variety of applications, such as automotive and aerospace applications, to provide information to the driver or pilot while allowing simultaneous forward visibility. In some instances, the head-up display system 14 may be provided behind the windshield 54 and projecting from the instrument panel 58 (FIG. 1), while in another example, the electro-optical assembly 10 May be positioned directly on the windshield 54 (Figure 2). The electro-optical assembly 10 may have any size, shape, bending radius, angle, or position. The electro-optical assembly 10 may be used to display a number of vehicle-related functions or operator assistance systems, such as alarms, warnings, or vehicle diagnostics. In the illustrated example, the speed of the vehicle 18 is displayed on the electro-optic assembly 10.

With respect to the head-up display system 14, the image projected onto the electro-optical assembly 10 should be bright enough to be visible under any conditions. This is a particularly challenging task when the light outside the vehicle 18 is bright. The contrast between the light from the projector 46 and the illumination behind the electro-optical assembly 10 can be low on bright, sunny days. Although a brighter, stronger illumination source (e.g., projector 46) improves contrast, increasing the display brightness may not be the most economical solution, and may be sufficient to provide reasonable contrast in very bright daylight conditions The bright display will be too bright for other conditions. Control can be used to deal with variations in luminance, but certain backgrounds always change in a moving vehicle and depend in part on the position of the driver's eye. According to one example, the electro-optic assembly 10 can be configured to lower the transmittance and / or to increase the contrast ratio.

Depending on the application, a higher or lower transmittance in the transparent state, a different reflectance value for an optimal contrast ratio, and / or a dynamic range of a wider transmittance level may be required. The range of initial reflectance and transmittance properties is more complicated by the ability of the projector 46 to be used with the head-up display system 14 and the light output capability of the projector 46, together with the light transmittance level for the windshield 54 It becomes. The windshield 54 will have a direct impact on the image contrast ratio and visibility from the head-up display system 14. There are a number of factors that affect the transmittance level of the windshield 54. The minimum light transmittance is based on the regulations at the place where the vehicle 18 is sold, but there may be a higher transmittance level based on how the vehicle 18 is mounted and sold. The range of such factors requires a solution that can be adapted to different vehicle and environmental conditions.

Another aspect to consider when using the head-up display system 14 is secondary reflections from the first surface 22A to the fourth surface 26B of the first and second substrates 22,26. Reflections from the first surface 22A to the fourth surface 26B are not perfectly aligned with the primarily reflected image (e.g., due to the geometry of the components of the electro-optical assembly 10) You can create a dual image effect from secondary reflections. A dual image that may be formed from secondary reflections from the first surface 22A to the fourth surface 26B is projected by the projector 46 and the primary image reflected by the electro- Or make it appear indefinitely.

According to one example, the electro-optical assembly 10 includes both two about 1.6 mm glass substrates (e.g., first and second substrates 22, 26) bent at a spherical radius of about 1250 mm . Different thicknesses for the first and second substrates 22, 26. In another example, the first and second substrates 22, 26 may be bent to have a "free-form" shape. The desired shape is that the resulting primary reflected image is "seen " in front of the electro-optical assembly 10 and in front of the vehicle 18. [ The exact surface contour required to obtain such a characteristic is a function of the nature of the projector 46, the projector 46 and driver position, as well as the position of the electro-optic assembly 10 relative to the other two positions. Having an image projected forward of the vehicle 18 allows the driver to acquire the desired information without changing their focal length. In a typical head-up display located within the vehicle 18, the driver ' s eyes are often refocused to a shorter viewing distance, thereby shortening the time spent on viewing the road. Also, then, the driver's eye will also have to be refocused to the front of the road, which further shortens the time spent on observing the road and front situation. The shape of the electro-optic assembly 10 should also be selected to preserve the basic characteristics of the projected image (i.e., to preserve the aspect ratio of the image so that the straight line remains straight).

Referring now to FIG. 3, the first substrate 22 includes a first surface 22A and a second surface 22B. The second surface 22B may be coated with indium tin oxide having a sheet resistance of about 12 ohms / sq. The first surface 22A may be concave and coated with chromium (Cr). The coated first substrate 22 may have a transmittance of about 37.8% and a reflectivity of about 25.4%. The second substrate 26 defines a third surface 26A and a fourth surface 26B. The third surface 26A may be coated with indium tin oxide having a sheet resistance of about 12 ohms / sq.

From the first surface 22A, the electro-optic assembly 10 may have a transparent state reflectance of about 25% and a transmissivity of about 24%. The electro-optical assembly 10 may have a transmittance of about 10.5% of the bottom or bottom state, and a bottom end reflectance of about 15% from the first surface 22A. Alternatively, in another example, the transmittance of the top, or top, state of the electro-optic assembly 10 may be 45% or even 60% greater. The characteristics of the electro-optic assembly 10 may also be varied such that the lower transmittance in the dark state is less than 7.5% or even less than 5%. In some instances, reduced transmittance levels up to 2.5% or less may be desirable. Increasing the upper transmittance can be achieved by the use of coatings and materials having a low water absorption, as will be described below. A lower bottom transmittance can be obtained through inclusion of a material having a higher absorption rate. (E. G., The spacing between the first and second substrates 22,26) where the low mass absorbing material acquires a higher absorbency in the electro-optical material and in the activated state when a wide dynamic range is desired, ≪ / RTI > Those skilled in the art will recognize that there are a number of coatings and combinations of electro-optical materials, cell spacing, and coating conductivity levels that can be selected to achieve particular device properties.

In order to provide current to the first and second substrates 22 and 26 and the electro-optic medium 38, an electrical element is disposed on opposite sides of the first and second substrates 22 and 26 (e.g., 2 surface 22B and the third surface 26A) to generate a potential therebetween. In one example, the J-clip can be electrically coupled to each electrical element, and the element wire extends from the J-clip to the primary printed circuit board. In order to provide the greatest surface area through the electro-optical assembly 10, electrical contact is placed along one side of the device. In such an example, there is an offset rear plate and top plate to allow electrical contact such as a bus clip. Other electrical contact designs are possible, including the use of conductive inks or epoxies.

According to various examples, the electro-optic medium 38 may be an electrochromic medium. In the electrochromic example, the electro-optic medium 38 may comprise at least one solvent, at least one positive electrode material, and at least one negative electrode material. Typically, both the anode and cathode materials are electroactive and at least one of them is electrochromic. It is to be understood that, regardless of its conventional meaning, the term " electroactive "may mean a substance that undergoes a modification of its oxidation state upon exposure to a particular potential difference. It will also be appreciated that the term "electrochromic" may refer to a material that exhibits a change in its extinction coefficient at one or more wavelengths when exposed to a particular potential difference, regardless of its conventional meaning. The electrochromic component can be a color or opacity that is changed by the current such that the color or opacity changes from the first phase to the second phase when current is applied to the material, Includes affected substances. Electrochromic components are described in U.S. Patent No. 5,928,572 entitled " Electrochromic Layer And Devices Comprising Same ", U.S. Patent No. 5,998,617 entitled " Electrochromic Compounds ", which is incorporated herein by reference in its entirety, U.S. Patent No. 6,020,987 entitled "Electrochromic Medium Capable Of Producing A Pre-selected Color", U.S. Patent No. 6,037,471 entitled "Electrochromic Compounds", entitled "Electrochromic Media For Producing A Pre- US Patent No. 6,141,137 entitled " Selected Color "; U.S. Patent No. 6,241,916 entitled "Electrochromic System"; U.S. Patent No. 6,193,912 entitled "Near Infrared-Absorbing Electrochromic Compounds And Devices Comprising Same" U. S. Patent No. 6,249, 369 entitled " Coupled Electrochromic Compounds With Photostable Dication Oxidation States ", and entitled " Electrochromic Media With Concentration Enhanced St < / RTI > Ability, Process For The Preparation Thereof and Use In Electrochromic Devices ", U.S. Patent No. 6,137,620; U.S. Patent Application Publication No. 2002/0015214 A1 entitled " Electrochromic Device "; And International Patent Application No. PCT / US98 / 05570 entitled " Electrochromic Polymer System ", entitled " Electrochromic Polymeric Solid Films, Manufacturing Electrochromic Devices Using Such Solid Films, US Patent Application No. PCT / EP98 / 03862, entitled " Electrochromic Polymeric Solid Films, Manufacturing Electrochromic Devices Using Such Solid Films, And Processes For Making Solid Films And Devices & Layer component, a multi-layer component, or a polyphase component, as described in U.S. Pat. The first and second substrates 22, 26 are not limited to glass elements, but may also be any other element having a partially reflective, partially transmissive nature.

According to various examples, the perimeter band of the electro-optic assembly 10 may be modified by adding or removing material to seal or obscure the seal 30 and the electrical contact material. In a first example, the outer perimeter of the first surface 22A and the fourth surface 26B may be etched to provide a substrate having a fogged periphery. In the fogged perimeter example, the perimeter band can be used to damage both the first surface 22A and the fourth surface 26B using a CO ₂ laser to form a fogged band of approximately 4 mm wide . Additionally or alternatively, the edges of the first surface 22A and the fourth surface 26B may be polished and / or polished. It is also contemplated that a spectral filter material (e.g., chrome or metal ring) or light scattering material may be applied to the first and / or second substrate 22, 26 (e.g., first surface 22A through fourth surface 26B ) To assist in concealing the seal 30. The spectral filter can block the observation of the seal 30 and also provide UV protection for the seal 30. In another example of a spectral filter, chromium oxynitride or other dark coating may be deposited around the electro-optic assembly 10 to create a dark ring that acts as a spectral filter. The spectral filter material may be selectively deposited or deposited over the entire surface and then selectively removed to produce a peripheral band using, for example, selective laser ablation. Additionally or alternatively, the seal 30 may be generally transparent, colorless, or may be configured to scatter light. In such an example, the fogged band may extend slightly inward of the seal 30. It will be appreciated that any of the techniques described above for concealing the seal 30 may be used alone or in combination with other disclosed concealment techniques for the seal 30.

In the illustrated example, each of the first and second substrates 22, 26 includes a rounded edge 62 and a non-rounded electrical contact edge 66. The non-rounded electrical contact edge 66 may be desirable for easy electrical contact and may be located on the first and second substrates 22 and 26 along the electrical contact edge 66 when the device is supported by an edge. You do not need to round it. Any exposed edges on the electro-optic assembly 10 can generally be rounded. The radius of curvature of the rounded edge 62 may be greater than about 2.5 mm.

Still referring to FIG. 3, the electro-optical assembly 10 may include a semi-permeable coating 70, an anti-reflective coating 80, and an anti-scratch coating 90. In the illustrated example, the semi-permeable coating 70 is located proximate to the first surface 22A, but additionally or alternatively, it may be located on the second surface 22B without departing from the teachings provided herein . In the illustrated example, the anti-reflective coating 80 is positioned on the first surface 22A, the third surface 26A and the fourth surface 26B, but such an anti-reflective coating 80 is additionally or alternatively It will be understood that the present invention can be positioned on the second surface 22B without departing from the teachings provided herein. In some instances, the anti-reflective coating 80 is positioned on at least one of the first surface 22A and the second surface 22B, and any of the first surface 22A and the second surface 22B is semi- May be located on a surface opposite the surface on which the coating 70 is located. The antireflective coating on the first surface 22A and the third surface 26A functions as an electrode (e.g., an antireflective electrode) that, in certain instances, can darken the electrochromic medium 38. It will be appreciated that, in certain instances, when the semipermeable coating 70 is placed on the second surface 22B, it may also serve a dual purpose and serve as an electrode. In the illustrated example, the scratch-resistant coating 90 is positioned proximate the first surface 22A and the fourth surface 26B. Although described as separate layers, the semi-permeable coating 70, the antireflective coating 80 and / or the scratch-resistant coating 90 share properties that function with other coatings, as will be described in more detail below You will understand that you can.

In a first embodiment, the semi-permeable coating 70 may be a thin metal layer (e.g., a metal-based coating 70) such as Cr or another metal. A potential disadvantage of using a single metal coating layer as the semipermeable coating 70 is that there is a defined relationship between reflectance and transmittance derived from the thickness of the metal. For example, a combination of reflectance and transmittance is shown in Figures 4A and 4B. From the foregoing figures, it can be seen that the single-metal layer generally does not allow the reflectivity and transmittance to be controlled independently. In another example of a semipermeable coating 70, a low-absorption layer comprising a material with a lower absorption rate than metal, such as indium tin oxide (ITO) or dielectric material, is deposited on the substrate (e.g., first substrate 22) And is positioned between the metal coating layers. Figure 5 shows the obtainable transmittance values according to reflectivity for the electro-optic assembly 10 having a single Cr layer and a double layer of ITO / Cr (e.g., semi-permeable coating 70) for different values of the Cr layer thickness Lt; / RTI > This layer increases the range of obtainable reflectivity and transmittance for the semipermeable coating 70 by allowing the reflectivity and reflected color to be tuned according to thickness and refractive index. In order to maximize the reflection intensity, the thickness is selected to satisfy the condition of the constructive interference as given by the following equation:

Where d is the layer thickness, m is the order of the interference, n is the layer refractive index, and [lambda] is the optical wavelength. In the case of the double layer of Fig. 5, the thickness of the ITO (e.g., low-absorption layer) is about 70 nm, which corresponds to m = 0 and lambda to 575 nm. The index of refraction of the low-absorption layer may be greater than about 1.3. In this case, the deposition conditions for ITO were chosen to increase the refractive index of ITO at 550 nm, from typical 1.8 to about 2.07, thereby increasing the reflectance according to the Fresnel equation at the normal incidence angle:

Where n ₁ and n ₂ correspond to the refractive index for the two media of the optical interface. The reflected color may also be tuned slightly by increasing or decreasing the thickness of the low-absorption layer. The metal layer may be selected from the list of metals provided below, and the material of the low-absorption layer may be selected from the list of dielectric materials provided below which meet the refractive index properties for this embodiment.

Although the example of a semi-permeable coating 70 having a dielectric-metal double layer provides a range of obtainable reflectivity and transmittance values over a single metal layer, tuning the refractive index and absorption rate of the material to achieve a particular reflectance and transmittance level It can still be a challenge. Accordingly, it may be advantageous to have a semi-permeable coating 70 that allows greater flexibility with respect to reflectivity and transmittance values, especially when lower transmittance values are considered. Thus, in another example of a semi-permeable coating 70, such properties can be obtained with multilayer coatings such as metal / dielectric / metal structures (MDM). In general, the M-layer of the MDM coating may be formed of a material selected from the group consisting of chromium, molybdenum, nickel, inconel, indium, palladium, osmium, tungsten, rhenium, iridium, rhodium, ruthenium, stainless steel, tantalum, titanium, Platinum group metals, zirconium, vanadium AlSi alloys, and alloys and / or combinations thereof. It will be appreciated that any of the metals described above may be used for an example of a single or dual layer of a semipermeable coating 70. In some instances, the combination of metal and dielectric material may vary depending on whether the semipermeable coating 70 is formed on the first surface 22A or the second surface 22B for durability or electrode properties. The dielectric material may be selected from one or more of the following: ITO, SnO _2, SiN, MgF _2, SiO _2, TiO _2, F: SnO _2, NbO _x, TaO _X, indium zinc oxide, aluminum zinc oxide, zinc oxide , Electrically conductive TiO ₂ , CeO _x , ZnS, chromium oxide, ZrO _x , WO ₃ , nickel oxide, IrO ₂ , NiO _x , CrO _x , NbO _x and ZrO _x , matter. It will be appreciated that any of the aforementioned dielectrics may be used for the dual layer example of the semipermeable coating 70. Figure 6 shows the reflectance and transmittance values for a multi-layer semipermeable structure (e. G., Semipermeable coating 70) having a Cr / ITO / Cr structure wherein the ITO thickness is 74.7 nm. Each point represents a specific reflectance / transmittance (R / T) value for a combination of the ^first and ^second Cr layer thicknesses. It can be seen that these two parameters span the range of transmittance values for a particular reflectance, and that the reflectance and transmissivity can be controlled separately within this range. As the thickness and the index of the intermediate-low absorption layer change, the relationship between the metal layers will change. The choice of metal will also change the relationship shown in FIG. In certain embodiments, two different metals may be selected for the top and bottom M-layers, and the D-layer may be further subdivided into sub-layers and may include materials of different refractive indices. Additional D- and / or M-layers may be added without departing from the teachings provided herein. Additional layers may be added to improve durability, adhesion, or to alter color and / or reflectance and transmittance range or robustness.

As found in metals, alternative materials that provide different R / T values can be used as the semi-permeable coating 70. TCOs and dielectric layers, along with materials such as TiO ₂ or diamond-like carbon (DLC), are other options, examples of which are illustrated in Figures 7 and 8 and Table 1.

Table 1: Transmittance and reflectance parameters for various semipermeable coatings on glass substrates.

Table 2: Integrated eye-weighted reflectance bottoms and corresponding transmittance of a monolayer metal anti-reflective coating on glass.

The example of Table 1 illustrates the eye-weighted reflectance (Yr) of various semipermeable coatings (e.g., semipermeable coating 70) on a glass substrate (e.g., first surface 22a of first substrate 22) , Transmittance (Yt), and absorptivity, wherein the reflectance is understood as the reflectance measured from the coated side of the substrate. The reflectivity from the reflective surface (e.g., first surface 22A) may be greater than about 15%, greater than about 20%, greater than about 25%, greater than about 30% , May be greater than about 40%, and may be greater than about 45%. For example, a semi-transmissive coating 70 having a single layer TCO, such as cold ITO, having a refractive index of about 2.07 at a wavelength of 550 nm will have a reflectivity of about 23% at a quarter wave optical thickness , While the semi-permeable coating 70 with TiO ₂ having a refractive index of about 2.34 at a wavelength of 550 nm will have a reflectivity of about 31.2% at a quarter wave optical thickness. The material and / or index of refraction may be selected such that the net reflectance is at an appropriate level. For most materials, the absorption is relatively low in these materials compared to metals. Figure 8 shows modeled values of reflectance and transmittance dependence for the electro-optic element 10 having a single layer ITO and ITO / TiO ₂ double layer semipermeable coating 70 according to ITO thickness. The TiO ₂ and ITO refractive indices used for the calculations were 2.32 and 2.11, respectively, and the thickness for the TiO ₂ layer remained constant at 34.5 nm. These layers enable higher reflectivity due to their large intrinsic refractive index or constructive interference effects. Figure 8 shows modeled values of reflectance and transmittance dependence for the electro-optic element 38 having a single layer of diamond-like carbon.

In another example with high contrast, the semi-transmissive coating 70 is based on a spectrally selective dielectric multilayer that is capable of reflecting a particular wavelength from the projector 46. Figure 9 illustrates a graph showing the spectral dependence of the reflectance for such a semipermeable coating 70. In such an example, the reflectance is about 90% to about 100% for wavelengths around 455, 550 and 630 nm. Other reflectance levels are possible and fall within the scope of this disclosure, and the reflectance bands can be centered at different wavelengths as needed to be compatible with the HUD display output. In some examples, the reflectance in the reflectance band for a spectrally selective dielectric multilayer is greater than about 35%, greater than about 55%, or greater than about 75%. An example of such a semi-permeable coating 70 is a multi-layered structure of refractive index layers of high-H and low-L index, such as Nb ₂ O ₅ for H and SiO ₂ or MgF ₂ for TiO ₂ , As shown in FIG.

의 유닛에서, a* 및 b*는 CIELAB 색상 시스템의 색상 파라미터이고, 전기-광학 조립체(10)의 색상은 약 20 미만, 약 10 미만, 또는 약 5 미만의 값을 가질 수 있다. 이들 측정법 중 모두는, 반사된 이미지의 색상이 정확한 것이거나 투사기(46)의 색상과 대략적으로 매칭되는 표면을 기술할 것이다. 다른 예에서, 원하는 색상을 달성하기 위해서 향상시키거나 보상하도록 투사기(46)의 출력에 매칭시키기 위해서, 반투과성 코팅(70)이 조율될 수 있다.When reflecting an image, it is important that the color rendering of the electro-optical assembly 10 be accurate. The output intensity of the different colors from the projector 46 can be adjusted to compensate for any variations in the reflectivity of the semi-transmissive coating 70. In some instances, the semi-permeable coating 70 will have a relatively constant reflectance over the visible spectrum. The reflected and transmitted color rendering of the electro-optical assembly 10 can be controlled by changing the thickness of the coating on each or a portion of the first surface 22A through the fourth surface 26B, the layer sequence, . Color rendering can be quantified in a number of ways. The color rendering index, or CRI, of the electro-optical assembly 10 may be greater than about 85, greater than about 90, or greater than about 95. Alternatively, c * =

A * and b * are color parameters of the CIELAB color system and the hue of the electro-optical assembly 10 may have a value of less than about 20, less than about 10, or less than about 5. All of these measurements will describe a surface in which the color of the reflected image is correct or approximately matches the color of the projector 46. In another example, the semipermeable coating 70 can be tuned to match the output of the projector 46 to enhance or compensate to achieve the desired hue.

According to another example, the semipermeable coating 70 is described in U.S. Provisional Patent Application No. 62 / 205,376, filed August 14, 2015, entitled " ELECTRO-OPTIC ASSEMBLY ", the entire disclosure of which is incorporated herein by reference. And may include any semipermeable coatings and layers disclosed in U. S. Pat.

Since the primary reflectivity of the head-up display system 14 is derived from the semi-transmissive coating 70, which is located on the first surface 22A or the second surface 22B of the electro-optical assembly 10, It is generally desirable to minimize secondary reflections from other surfaces (e.g., first surface 22A through fourth surface 26B where there is no semi-permeable coating 70) It is important. Thus, the use of an antireflective coating 80 may be advantageous. An example of the antireflective coating 80 may be a transparent conductive oxide. In connection with the example described herein, the second surface 22B and the third surface 26A may comprise transparent electrodes. ITO, F: SnO _2, a transparent conductive oxide (TCO) such as doped -ZnO, IZO, or other layers, such as electrical electrochromic system is generally used in optical devices. As noted above, the reflectivity of these materials is a function of coating thickness due to interference effects. The minimum reflectance can be obtained by adjusting the thickness of the conductive oxide coating (e.g., antireflective coating 80). The minimum reflectance exists at half wave optical thickness. Depending on the wavelength of the projector 46 of the head-up display system 14, the wavelength of the half-wave condition can be adjusted to obtain the net minimum reflectance value. For example, the reflectance of the ITO coating may be as small as 0.5% or less from the second surface 22B and the third surface 26A having a thickness of about 145 nm of the antireflective coating 80.

As noted above, the half wave thickness of ITO has a sheet resistance of about 12 ohms / sq. In some instances, this is not a sufficiently low sheet resistance to achieve rapid and uniform blackening of the electro-optic assembly 10. Thus, a lower sheet resistance value can be obtained using a thicker coating layer (e. G., Antireflective coating 80). In order to maintain the minimum reflectivity value for the antireflective layer 80, the TCO or ITO needs to be a multiple of the half-wave thickness. For example, the thickness of the antireflective coating 80 can be the entire wave, three half waves, or the like. As the thickness of the antireflective coating 80 is moved to a larger multiple of the half-wave coating, the reflectance is still higher than the local minimum, but half-wave reflectance. The reflectance of the second surface 22B or the third surface 26A, having an electro-optic medium 38 having a refractive index of 1.45 and ITO of a refractive index of 1.85, is about 0.5%. In the case of an antireflective coating 80 that is twice the half-wave thickness, the reflectance is about 1.25%, and for a coating that is three times the half-wave thickness, the reflectance is about 1.7%. As noted above, the reflectivity will decrease with decreasing refraction index of ITO, which can be obtained by making it more conductive. Optical media 38 or substrate (e.g., first and / or second substrate 22, 26) media or an electro-optic medium 38 ) And by increasing the index of refraction of the substrate medium, the reflectivity can also be reduced. The refractive index of the TCO or ITO example of the second surface 22B and the antireflective coating 80 on the third surface 26A may be less than about 2.0, less than about 1.92, or less than about 1.88. The refractive index of the electro-optic medium 38 may be greater than about 1.2, greater than about 1.4, or greater than about 1.5. The refractive index of the substrate medium may be greater than about 1.4, greater than about 1.6, or greater than about 1.8. The reflectance of the second surface 22B and the third surface 26A may be less than about 2%.

The adjustment of the reflectance of the surface that does not have the semi-permeable coating 70, such as the first surface 22A to the fourth surface 26B, is such that the semi-permeable coating 70 is applied to the first surface 22A or the second surface 22B, It is important to minimize the dual image depending on whether or not it is on. Due to the refractive index of the first and / or second substrate 22, 26 (glass or plastic of about 1.5) and the refractive index of the incident medium (air of 1.0), the first surface 22A and the fourth surface 26B ) Has a high reflectance of about 4% and is most likely to generate undesirable double images. The permissible reflectivity of the second surface 22B and the third surface 26A as well as the first surface 22A and the fourth surface 26B depends on the material that is between the surface and the observer (e.g., the operator) And its properties. The permissible absolute reflectance level can be higher when the absorbing material is between the surface and the observer. Accordingly, the overall absorption rate is changed within the component between the observer and the surface, and the absolute absorption from the first surface 22A, the second surface 22B, the third surface 26A, and the fourth surface 26B, The reflectivity limit can be small when less light is attenuated between the surface and the observer, such as when a larger dynamic range is desired and / or when the low-reflectance of the first surface 22A is the design goal. The exact impenetrable reflectance threshold will vary depending on the details of the head-up display system 14. The reflectance of the second surface 22B, the third surface 26A and the fourth surface 26B may be less than about 2%.

In another example, the antireflective coating 80 can be a dielectric antireflective coating, such as a S / H / L laminate, where S is the first or second substrate 22, 26, H / L is high May be a multilayer stack of alternating materials having a low index of refraction. Alternatively, the anti-reflective coating 80 may be a graded coating obtained with a nanostructured, textured surface or other type of graded coating. In such an example, the antireflective coating 80 may be tuned to provide a desired reflectivity level with the desired color reflected from the surface. However, such an example of the antireflective coating 80 may be fragile and requires an improved antireflective coating that has better durability characteristics while reducing the reflectivity of the light observed by the driver.

In another example, an anti-reflective coating 80 may be added to the fourth surface 26B to minimize the intensity of multiple reflections when viewing the electro-optical assembly 10 from the first surface 22A. The reflectance of the fourth surface 26B may be less than 1%. The head-up display system 14 can be optimally operated when the reflectance of the fourth surface 26B is less than about 0.5%. For example, the antireflective coating 80 may comprise a dielectric antireflective laminate having four layers of alternating high and low refractive index materials, wherein the sequence of the laminate is SHLHL, H represents a high-index material, and L represents a low-index material. The thickness of the layer starting from the first layer adjacent to the fourth surface 26B is about 0.0617, 0.0796, 0.4758 and 0.2279 FWOT. Examples of high-index dielectric materials are Nb ₂ O ₅ , Ta ₂ O ₅ , TiO ₂ , and examples of low-index dielectric materials are SiO ₂ and MgF ₂ . An example of a metal containing an antireflective coating 80 is a single layer of metallic material such as Cr, Co, Ir, Mo, Pt, Ta, Zr, W, Re, or Va, . It is also important to minimize the reflectance from the second surface 22B and the third surface 26A. The reflectivity at these surfaces is a function of the refractive index of the first and second substrates 22 and 26, the coating stack on the substrates 22 and 26, and the electro-optic medium 38 in contact with the coating stack. The reflectance can also be a function of the coating thickness. In the case of a solution-based electrochromic device, the use of a fluid having an index of refraction that more closely matches the index of refraction of the coating will reduce reflectivity. Assuming ITO as an electrode for the electro-optical assembly 10 and assuming an ITO index of refraction of about 1.8, the reflectance normal to the surface of each coating / fluid interface is given by the Fresnel equation given above. If the fluid has an index of refraction of about 1.2, the reflectance of each coating / fluid interface may be about 4%. In a fluid having an index of refraction of 1.4, the reflectance of each coating / fluid surface may be about 1.6%. The intensity of some of the multiple reflections can be reduced by darkening the electro-optical assembly 10. While this also reduces forward visibility, there may be times when it is quite advantageous to have an electro-optic assembly 10 that darkens and thereby improves contrast and reduces dual imaging. One other consideration is the transmittance of the coating of the first surface 22A. A lower transmittance reduces forward visibility, but also reduces dual images from the second surface 22B, the third surface 26A and the fourth surface 26B.

Note that, unlike other anti-reflection applications, the problem solved is not the reflectivity as seen from the fourth surface 26B, but rather the reflectivity from the opposite direction (e.g., from the first surface 22A) It is important to do. Thus, the reflectance as seen from the fourth surface 26B does not actually have any reflectivity constraints. This particular set of requirements can be resolved with a new antireflective coating designed on the basis of a thin metal layer. Thus, in another example, the anti-reflective coating 80 may comprise one or more thin metal coatings. It has been found that the reflectivity of a thin metal coating will vary with the viewing direction. For example, when a Cr coating is applied to a glass substrate (or a material having a comparable index of refraction), the reflectance from the coated side will steadily increase. This is a generally expected behavior for metal coatings. Conversely, when observed through glass, the reflectivity will have an alternative behavior. As the thickness of the metal coating layer increases, the reflectivity lowers initially and progresses through the minimum until the reflectivity is steadily increased, as expected for the metal layer. Such an effect occurs in a very thin coating layer. Examples of reflectance along the wavelengths within the visible range include glass / air interfaces in the uncoated state, glass / air interfaces with a four layer HL anti-reflective coating, and glass / air interface with a thin Cr example of the anti- The interface is shown in FIG. From this it can be observed that the thin metal layer example of the antireflective coating 80 reduces a significant amount of reflectance from the glass from an observer's perspective. Examples of metal AR coatings may be a single layer or multiple layers of metal materials such as Cr, Co, Ir, Mo, Pt, Ta, Zr, W, Re, or Va, or alloys containing these elements. The total thickness of the metal layer should be from about 0.1 nm to about 5 nm.

(E. G., Antireflective coating 80), as viewed through the substrate (e.g., first and / or second substrate 22 and 26) Is shown in Fig. In such an example, the reflectance is indicated for a substrate comprising an uncoated surface and an anti-reflective coated surface. Accordingly, the reported reflectivity values are relatively high, and the net reflectance from the coated surface can be obtained by subtracting about 4.2% from the reported values. It can be seen from Fig. 10 that the metal exhibits a characteristic minimum of reflectance at a thickness of 0.5 to 4.0 nm. Table 2 illustrates, by way of example, the vertically-incident integrated eye-weighted reflectance of a glass substrate having an example of the anti-reflective coating 80 as viewed from the uncoated glass side. The reflectance from the uncoated glass substrate was also described in Table 2.

The examples in Table 3 show eye-weighted reflectance (Yr), transmittance (Yt) and absorptivity of various electro-optical elements with different semipermeable coatings 70, TCO coatings and anti-reflective coatings 80, And toward the first surface 22A. The example illustrates a broad range of transmittance values that can be obtained while maintaining a similar reflectance of about 25% and an intermediate reflected color having an absolute reflected a * and b * value of less than 3 and a C * value of less than 3 do.

Table 3: Transmittance and reflectance parameters for various semipermeable coatings on electro-optic assemblies:

As shown in Table 2, some of the thin metal examples of the antireflective coating 80 may have reflectance values in excess of zero for their optimal antireflective situations. This is uncommon in the antireflective coating 80 because it can be a challenge to prevent reflection over a wide wavelength range. The aforementioned thin metal antireflective coating 80 may be further improved by the addition of a thin dielectric layer positioned between the substrate (e.g., the first substrate 22) and the metal coating layer. Table 4 below shows the values that can be obtained for a chromium metal coating example of an antireflective coating 80 using a thin film model. The reflectance is substantially reduced in addition to the dielectric layer. The desired thickness and refractive index of such a dielectric layer will vary depending on the metals used and the requirements of the application. The index of refraction of the dielectric layer may be less than about 2.4 or less than about 2.0. The thickness of the dielectric layer may be less than about 50 nm or less than about 35 nm.

Table 4:

The reflectivity of the metal or dielectric metal laminate example of the antireflective coating 80 may be further reduced by modifying the refractive index of the metal layer. This can be achieved by adding small dopants or additives such as nitrogen, oxygen, both or other elements to the metal. For example, the chromium layer was sputtered with 5% oxygen and 5% nitrogen and the reflectances were 4.24% and 4.25%, respectively. Different levels of gas can be used in the sputtering atmosphere to change the optical properties of the metal. The percentage of the dopant gas source may be varied experimentally to optimize reflectivity as needed. The refractive index relationship described above can be used to induce optimization of the material for the desired antireflective properties.

The exposed coatings (e.g., the semi-permeable coating 70 and the antireflective coating 80) on the first surface 22A and the fourth surface 26B can be used to remove environmental contaminants, Can be obtained. Accordingly, the coating will be regularly cleaned to have the best possible image. If the coating is not quadratic, the coating may be scratched or otherwise damaged by a cleaning solvent or method. Thus, it may be advantageous for these materials to be durable or to add an anti-scratch coating 90. In one example, the semi-permeable coating 70 may be formed of a diamond-like carbon (DLC) material. DLC materials are reflective, somewhat absorbent and highly durable (e.g., scratch-resistant). An example of a semi-permeable coating 70 comprising such a material would be stable in an automotive environment. Figure 7 shows the reflectance and transmittance relationships for the single layer DLC on the first surface 22A according to the antireflective coating and the thickness on the fourth surface 26B. In addition, the DLC material can be used in the scratch-resistant coating 90. For example, if additional durability is desired for a thin metal or other type of antireflective coating 80 as described above, a top DLC layer may be added to the laminate as an anti-scratch coating 90. Since the DLC typically has a relatively high index of refraction, other layers may need to be optimized or adjusted to achieve the desired balance between reflectivity and durability.

One of the functions of the variable transmittance electro-optic assembly 10 for the head-up display system 14 is to allow viewing through the assembly 10 at different transmit level levels for viewing the environment outside the vehicle 18. [ will be. In one example, it may be important to match the hue of light passing through the electro-optic assembly 10 in a transparent and / or dark state with light that does not pass through the assembly 10. In other words, the color rendering index of the transmitted light should be relatively high, similar to the reflected CRI discussed herein. The color rendering index of the transmitted light should be greater than about 75, more preferably greater than about 85, even more preferably greater than 90, and most preferably greater than about 95. These values may be related to the high-transmittance state, the low-transmittance state, and / or the intermediate transmittance state of the electro-optic assembly 10. The reflected and transmitted color of the coating (e.g., semi-permeable coating 70, antireflective coating 80, and / or scratch-resistant coating 90), along with any absorptance present in the material, Will play a role in that. Similarly, the absorption rate of the electro-optic medium 38 in the transparent and dark states will serve as a factor in the CRI calculation. In some embodiments, the characteristics of the coating and the electro-optic medium 38 can be tuned or adjusted so that the net color has an appropriate CRI. For example, if one or more of the coatings have a blue absorption rate, the net-transmittance through the electro-optic assembly 10 may be adjusted such that the electro-optic medium 38 has a yellow absorption component < . ≪ / RTI >

It will be understood by those skilled in the art that the structure of the disclosure and other elements described are not limited to any particular material. Other exemplary implementations of the disclosure herein may be formed from a wide variety of materials, unless otherwise indicated herein.

For purposes of this disclosure, the term "coupled" (of any type, such as a couple, coupling, Means a direct or indirect connection of two components to each other. Such a connection can be inherently fixed and inherently dynamic. Such a connection can be achieved by two components (either electrically or mechanically) and any additional intermediate members integrally formed as one single piece with one another or with two components. Such a connection may be inherently permanent and may be inherently removable or releasable unless otherwise specified.

It is also important to note that the construction and arrangement of the elements of the present invention, as illustrated in the exemplary embodiments, are exemplary only. Although only a few implementations of the present innovation have been described in detail in this disclosure, those skilled in the art will appreciate that many modifications (e. G., Dimensions of various elements , Dimensions, structures, shapes and ratios, parameter values, mounting arrangements, variations in material usage, color, orientation, etc.). For example, an element depicted as being formed in one piece may be composed of a plurality of parts, or the elements shown in the plurality of parts may be integrally formed and the operation of the interface may be reversed or otherwise changed, And / or the length or width of the member or other element of the connector or system may be varied and the nature or number of the adjustment position provided between the elements may be varied. It should be noted that the elements and / or assemblies of the system may be constructed from any of a wide variety of materials that provide sufficient strength or durability in any of a wide variety of colors, textures, and combinations thereof. Accordingly, all such modifications are intended to be included within the scope of this innovation. Other permutations, modifications, variations, and omissions may be made in the design, operating conditions and arrangements of the preferred and other exemplary embodiments without departing from the spirit of the present technology.

It will be appreciated that any of the described processes or steps within the process described may be combined with other disclosed processes or steps to form a structure within the scope of the present invention. The exemplary structures and processes disclosed herein are for illustrative purposes only and should not be construed as limiting.

It is also to be understood that variations and modifications can be made in the structures and methods described above without departing from the concept of the present invention, and that such concepts are encompassed by the following claims, unless expressly specified otherwise in their language Should be understood as being intended.

Claims (23)

An electro-optical assembly configured to be operatively connected to a head-up display system of a vehicle, comprising:
A first substrate;
A first surface;
A first substrate comprising a second surface;
A second substrate;
A third surface;
A second substrate comprising a fourth surface,
The first substrate and the second substrate being configured to be held in a parallel spaced relationship and to be sealed around a periphery of the first and second substrates;
A semi-permeable coating positioned on at least one of the first and second surfaces of the first substrate;
An anti-reflection electrode positioned on at least one of the second and third surfaces;
An anti-reflective coating positioned on said fourth surface; And
An electrochromic medium positioned between a second surface of the first substrate and a third surface of the second substrate,
Wherein the electro-optic assembly is configured to reflect an image from a projector of a head-up display system of a vehicle. 2. The assembly of claim 1, wherein the semipermeable coating is located on a first surface of the first substrate. 2. The assembly of claim 1, wherein the semipermeable coating is positioned on a second surface of the first substrate. 4. The electro-optical assembly of any one of claims 1 to 3, wherein the semipermeable coating has a reflectance of about 15% to about 45%. 5. A method according to any one of claims 1 to 4, wherein the anti-reflection electrode comprises indium tin oxide having a thickness approximately equal to a multiple of a half wave thickness of light from the projector, , An electro-optical assembly. 6. The assembly of any one of claims 1 to 5, wherein the electro-optic assembly has a high state reflectivity of about 25% and a high state transmittance of at least about 24%. 7. The assembly of any one of claims 1 to 6, wherein the electro-optic assembly has a bottom transmittance of at most 10.5%. 8. The assembly as claimed in any one of claims 1 to 7, wherein the first and second substrates are two 1.6 mm glass substrates both bent to have a free-form configuration. 9. A method according to any one of claims 1 to 8, wherein the semipermeable coating comprises at least one of a spectrally selective dielectric multilayer, a diamond-like carbon coating, a dielectric layer, and a dielectric- Optical assembly. 10. The method according to any one of claims 1 to 9,
Further comprising a diamond-like carbon coating located on the semipermeable coating. An electro-optical assembly configured to be operatively connected to a head-up display system of a vehicle, comprising:
The first substrate comprises:
A first surface;
A second surface;
The second substrate comprises:
A third surface;
The first substrate and the second substrate being configured to be disposed in a parallel spaced relationship and to be sealed along a periphery of the first and second substrates;
A semi-permeable coating disposed on at least one of the first and second surfaces, the semi-permeable coating comprising a low-absorbing layer and at least a first metallic layer; And
An electrochromic medium positioned between a second surface of the first substrate and a third surface of the second substrate,
The reflectance is substantially unchanged,
Wherein the electro-optic assembly is configured to control the transmittance from a transparent state to a dark state,
Wherein the electro-optic assembly is configured to reflect an image from a projector of a head-up display system of a vehicle. 12. The assembly of claim 11, wherein the anti-reflective coating is positioned on at least one of the first and fourth surfaces of the second substrate. The method as claimed in claim 11 or 12,
Further comprising an anti-reflection electrode on at least one of the second surface and the third surface, wherein the anti-reflective electrode comprises a transparent conductive oxide (TCO). 14. The assembly of claim 12 or 13, wherein the antireflective coating is located on the fourth surface, and wherein the antireflective coating comprises a metal-based antireflective coating. 15. The electro-optic assembly of any one of claims 12 to 14, wherein the electro-optic assembly is configured to reflect an image at a reflectance of about 15% to 35%. 16. The electro-optic assembly of any one of claims 11 to 15, wherein the electro-optic assembly is configured to control transmittance in a transparent state from about 24% to about 60%. 17. The assembly as claimed in any one of claims 11 to 16, wherein at least one of the reflected light and the transmitted light has a color rendering index of greater than 85. 18. A method according to any one of claims 11 to 17, wherein the semipermeable coating further comprises a second metal layer, the low-absorption layer being positioned between the first metal layer and the second metal layer, Optical assembly. 19. The electro-optical assembly according to any one of claims 11-18, wherein the electro-optic assembly is configured to control the transmittance to less than 7.5% in a dark state. An electro-optical assembly comprising:
A substrate defining a first surface and a second surface;
A semi-permeable layer positioned on a first surface of the first substrate, the semi-permeable layer comprising a metal-dielectric-metal (MDM) structure having a reflectance of about 15% to 35%;
A second substrate defining a third surface and a fourth surface;
An antireflective electrode positioned on a second surface of the first substrate and a third surface of the second substrate, the antireflective electrode comprising a transparent conductive oxide;
An anti-reflective coating on the fourth surface of the second substrate; And
An electrochromic medium positioned between a second surface of the first substrate and a third surface of the second substrate and operable between a transparent state and a dark state,
The reflectance from the antireflective coating and the antireflective electrode is less than 1% each,
The transparent state transmittance is about 24% to 45%, the dark state transmittance is less than about 7.5%
Wherein the electro-optic assembly is configured to be operatively connected to a head-up display system for a vehicle. 21. The assembly of claim 20, wherein the anti-reflective coating comprises a plurality of layers of alternating material having a high-index of refraction and a low-index of refraction. 22. The electro-optic assembly of claim 20 or 21, wherein the anti-reflective coating comprises a dopant. 23. The electro-optical assembly according to any one of claims 20-22, wherein the first surface of the first substrate and the fourth surface of the second substrate are configured to have rounded edges.

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